Assumption of indebtedness.

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- Definition

Business acquisition debt position exceeds.

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- Definition

Business acquisition number of shares

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Business Acquisition, shares outstanding.

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- Definition

Business acquisition shares outstanding exchanged.

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- Definition

Business disposition.

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- Definition

Estimated liabilities for future site separation commitment charge.

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Liabilities recorded from disposal group including discontinued operation.

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Payments for financial contributions for divestiture of businesses.

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Amount of direct costs of the business combination including legal, accounting, and other costs incurred to consummate the business acquisition.

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No definition available.

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- Definition

Number of shares of equity interests issued or issuable to acquire entity.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 805
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

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- Definition

Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

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No definition available.

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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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Acquisitions and Divestitures - Additional Information (Detail) $ in Millions		3 Months Ended		6 Months Ended
	Aug. 01, 2024 USD ($) shares	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jul. 26, 2024 $ / shares
Warrick Rolling Mill [Member] \| Disposal Group, Held-for-Sale, Not Discontinued Operations [Member]
Business Disposition [Line Items]
Estimated liabilities for future site separation commitment charge \| $		$ 4		$ 15	$ 17
Payments against the reserve \| $		5	$ 11	12	$ 25
Remaining reserve \| $		$ 14		$ 14
Alumina Limited [Member] \| Subsequent Event [Member]
Business Disposition [Line Items]
Agreed ratio value per share \| $ / shares						$ 1.45
Aggregate purchase consideration \| $	$ 2,800
AWAC [Member] \| Alumina Limited [Member] \| Subsequent Event [Member]
Business Disposition [Line Items]
Non-controlling interest, ownership percentage	40.00%
AWAC [Member] \| Alcoa Corporation [Member]
Business Disposition [Line Items]
Ownership interest percentage		60.00%		60.00%
Scheme Implementation Deed [Member] \| Alumina Limited [Member] \| Subsequent Event [Member]
Business Disposition [Line Items]
Business acquisition, shares outstanding \| shares	2,760,056,014
Business acquision, number of shares \| shares	4
Debt position exceeds \| $	$ 420
Assumption of indebtedness \| $	385
Deferred tax assets \| $	$ 100
Scheme Implementation Deed [Member] \| New Alcoa Preferred Stock [Member] \| Alumina Limited [Member] \| Subsequent Event [Member]
Business Disposition [Line Items]
Business acquisition, shares outstanding \| shares	141,625,403
Business acquisition, shares exchanged \| shares	4,041,989
Scheme Implementation Deed [Member] \| New Alcoa Preferred Stock [Member] \| Alumina Limited [Member] \| Subsequent Event [Member]
Business Disposition [Line Items]
Business acquisition, shares issued \| shares	0.02854
Scheme Implementation Deed [Member] \| Alcoa Common Stock [Member] \| Alumina Limited [Member] \| Subsequent Event [Member]
Business Disposition [Line Items]
Business acquisition, shares issued \| shares	0.02854
Business acquisition, shares exchanged \| shares	78,772,422
Scheme Implementation Deed [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Alumina Limited [Member] \| Subsequent Event [Member]
Business Disposition [Line Items]
Recognized transaction costs \| $	$ 9
Scheme Implementation Deed [Member] \| AWAC [Member] \| Alumina Limited [Member] \| Subsequent Event [Member] \| Maximum [Member]
Business Disposition [Line Items]
Ownership interest percentage	100.00%
Scheme Implementation Deed [Member] \| AWAC [Member] \| Alumina Limited [Member] \| Subsequent Event [Member] \| Minimum [Member]
Business Disposition [Line Items]
Ownership interest percentage	60.00%
Scheme Implementation Deed [Member] \| CHESS Depositary Interests [Member] \| Alumina Limited [Member] \| Subsequent Event [Member]
Business Disposition [Line Items]
Business acquisition, shares issued \| shares	0.02854